A 3rd generation partnership project long term evolution (3GPP LTE) (hereinafter, referred to as ‘LTE’) communication system which is an example of a wireless communication system to which the present invention can be applied will be described in brief.
FIG. 1 is a diagram illustrating a network structure of an Evolved Universal Mobile Telecommunications System (E-UMTS) which is an example of a wireless communication system. The E-UMTS is an evolved version of the conventional UMTS, and its basic standardization is in progress under the 3rd Generation Partnership Project (3GPP). The E-UMTS may be referred to as a Long Term Evolution (LTE) system. Details of the technical specifications of the UMTS and E-UMTS may be understood with reference to Release 7 and Release 8 of “3rd Generation Partnership Project; Technical Specification Group Radio Access Network”.
Referring to FIG. 1, the E-UMTS includes a User Equipment (UE), base stations (eNode B; eNB), and an Access Gateway (AG) which is located at an end of a network (E-UTRAN) and connected to an external network. The base stations may simultaneously transmit multiple data streams for a broadcast service, a multicast service and/or a unicast service.
One or more cells exist for one base station. One cell is set to one of bandwidths of 1.44, 3, 5, 10, 15 and 20 MHz to provide a downlink or uplink transport service to several user equipments. Different cells may be set to provide different bandwidths. Also, one base station controls data transmission and reception for a plurality of user equipments. The base station transmits downlink (DL) scheduling information of downlink data to the corresponding user equipment to notify the corresponding user equipment of time and frequency domains to which data will be transmitted and information related to encoding, data size, and hybrid automatic repeat and request (HARQ). Also, the base station transmits uplink (UL) scheduling information of uplink data to the corresponding user equipment to notify the corresponding user equipment of time and frequency domains that can be used by the corresponding user equipment, and information related to encoding, data size, and HARQ. An interface for transmitting user traffic or control traffic may be used between the base stations. A Core Network (CN) may include the AG and a network node or the like for user registration of the user equipment. The AG manages mobility of the user equipment on a Tracking Area (TA) basis, wherein one TA includes a plurality of cells.
Although the wireless communication technology developed based on WCDMA has been evolved into LTE, request and expectation of users and providers have continued to increase. Also, since another wireless access technology is being continuously developed, new evolution of the wireless communication technology will be required for competitiveness in the future. In this respect, reduction of cost per bit, increase of available service, use of adaptable frequency band, simple structure and open type interface, proper power consumption of the user equipment, etc. are required.
Recently, ongoing effort to standardize a follow-up technology for LTE is in progress by 3GPP. In the present specification, the technology is referred to as ‘LTE-A’. LTE-A system aims to support a wideband of maximum 100 MHz. To this end, the LTE-A system uses a carrier aggregation (CA) technology to achieve the wideband using a plurality of frequency blocks. In order to use a wider frequency band, the CA uses a plurality of the frequency blocks as a single huge logical frequency band. A bandwidth of each frequency block can be defined based on a bandwidth of a system block used in LTE system. Each of a plurality of the frequency blocks can be referred to as a component carrier (CC) or a cell.
And, in LTE system, it is able to support a duplex operation for dividing all available resources into a downlink resource (i.e., a resource used by a base station to transmit a signal to a UE) and an uplink resource (i.e., a resource used by a UE to transmit a signal to a base station). For example, a frequency division duplex (FDD) scheme or a time division duplex (TDD) scheme can be applied. A usage of each resource can be configured as either downlink (DL) or uplink (UL). According to legacy LTE system, the usage is designated by system information.
Recently, as one of methods of improving LTE/LTE-A system, regarding the duplex operation, discussion on a method of dynamically designating DL-UL configuration is in progress.